Self expanding stents are used either bare or in conjunction with a biocompatible graft material in endovascular therapies in which the stent is placed in a body lumen to reinforce the lumen or a tubular graft placed into the lumen.
Self expanding stents are generally formed from a resilient wire such as Nitinol™ or stainless steel and made in a zig-zag form with the ends joined to form a cylindrical or polygonal body. The cylindrical or polygonal body can be reduced in diameter by compressing the stent against its resilient forces to permit placement by endovascular techniques and then released to expand in a desired position in the vasculature. The joining of the ends of the resilient wire can be a problem because joining requires welding or soldering and the heating involved can induce brittleness around the joint.
Nitinol™ in particular, is difficult to join and the region around the joint may need to be annealed which could remove the resilient nature of the material. This invention proposes an alternative method of forming self expanding stents and a stent so formed or at least provides a practitioner with a useful alternative.
Throughout this specification the term distal with respect to a portion of the aorta, a deployment device or a prosthesis is the end of the aorta, deployment device or prosthesis further away in the direction of blood flow away from the heart and the term proximal means the portion of the aorta, deployment device or end of the prosthesis nearer to the heart. When applied to other vessels similar terms such as caudal and cranial should be understood.